DESCRIPTION: Mutational activation of ras oncogene products (p21 s) is involved in the loss of growth control in a high percentage of human tumors. Consequently, significant attention has focused on defining the biochemistry and pharmacology of p2ls, with the ultimate goal of developing inhibitors of p21 to be used as antitumor drugs. P21 S require extensive post-translational processing to express optimal transforming ability, including attachment of farnesyl and palmitoyl moieties to cysteine residues near the C-terminus. While several inhibitors of farnesyltransferase inhibitors have been described; the biochemistry and pharmacology of the palmitoylation step have not yet elucidated. During the initial funding period of this grant, we demonstrated that a natural product called cerulenin inhibits protein palmitoylation and inhibits the signaling activities of p21. Furthermore, we synthesized a series of alkyloxiranecarboxamides, including certain radiolabeled compounds, as cerulenin analogs, and some of these compounds were shown to be selective inhibitors of protein palmitoylation. This was the first demonstration of selective inhibitors of this molecular target. Analysis of protein alkylation by the radiolabeled compounds has identified a few candidate proteins for the heretofore unpurified human p21 acyltransferase (PATase) that palmitoylates Ras proteins. We are currently in a unique position to characterize this enzyme both biochemically and pharmacologically. In studies to be conducted under this Continuation, we will: 1) continue the isolation and biochemical characterization of human PATase; 2) design and synthesize additional inhibitors of PATase; 3) evaluate the anti-tumor potential of PATase inhibitors in vivo; and 4) further assess the biological consequences of inhibiting PATase in vitro. These efforts are logical and feasible extensions of work completed during the initial funding period. Overall, they should allow critical evaluation of PATase as a target for new anticancer drugs.